Description (Taken from the application): The major goal of the Molecular Histology Core B is to provide histological service to investigators in the Program Project grant. Our specific aims are (1) to measure by static and dynamic histomorphometry bone formation and resorption in murine bones, (2) to quantify bone mass and structure in murine bones using microcomputed tomography, as well as in the skeleton of living animals using peripheral quantitated computed tomography, (3) to ,quantify bone mechanical integrity using flexure and/or torsion tests to failure using a mechanical test system capable of tension-compression and/or torsion, (4) to analyze by immunofluorescence microscopy or immunohistochemistry the localization and extent of expression of bone factors and cytokines in bone from transgenic mice, carrying different promoter-reporter constructs or mice lacking or overexpressing specific receptors, and (5) to develop new histological techniques to substantiate and to elaborate further the results obtained by molecular biological and biochemical assays by investigators in the Program Project grant. The Molecular Histology Core is able to provide an efficient and specialized service that would not be possible for individual investigators to develop without a major investment of time, new personnel and money. The Core will develop a centralized data base on skeletal changes in transgenic mice for use by investigators at the University of Connecticut Health Center and eventually by other institutions. New information will be generated on the function of bone cells involved in growth, development and musculoskeletal diseases, such as osteoporosis.